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1. chapter 3
the interaction

2. The Interaction
• interaction models
– translations between user and system
• ergonomics
– physical characteristics of interaction
• interaction styles
– the nature of user/system dialog
• context
– social, organizational, motivational

3. What is interaction?
communication
user  system
but is that all … ?
– see “language and action” in chapter 4 …

4. models of interaction
terms of interaction
Norman model
interaction framework

5. Some terms of interaction
domain – the area of work under study
e.g. graphic design
goal – what you want to achieve
e.g. create a solid red triangle
task – how you go about doing it
– ultimately in terms of operations or actions
e.g. … select fill tool, click over triangle
Note …
– traditional interaction …
– use of terms differs a lot especially task/goal !!!

6. Donald Norman’s model
• Seven stages
– user establishes the goal
– formulates intention
– specifies actions at interface
– executes action
– perceives system state
– interprets system state
– evaluates system state with respect to goal
• Norman’s model concentrates on user’s view
of the interface

7. execution/evaluation loop
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal
system
evaluation
execution
goal

8. execution/evaluation loop
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal
system
evaluation
execution
goal

9. execution/evaluation loop
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal
system
evaluation
execution
goal

10. execution/evaluation loop
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal
system
evaluation
execution
goal

11. Using Norman’s model
Some systems are harder to use than others
Gulf of Execution
user’s formulation of actions
≠ actions allowed by the system
Gulf of Evaluation
user’s expectation of changed system state
≠ actual presentation of this state

12. Human error - slips and mistakes
slip
understand system and goal
correct formulation of action
incorrect action
mistake
may not even have right goal!
Fixing things?
slip – better interface design
mistake – better understanding of system

13. Abowd and Beale framework
extension of Norman…
their interaction framework has 4 parts
– user
– input
– system
– output
each has its own unique language
interaction  translation between languages
problems in interaction = problems in translation
S
core
U
task
O
output
I
input

14. Using Abowd & Beale’s model
user intentions
 translated into actions at the interface
 translated into alterations of system state
 reflected in the output display
 interpreted by the user
general framework for understanding interaction
– not restricted to electronic computer systems
– identifies all major components involved in interaction
– allows comparative assessment of systems
– an abstraction

15. ergonomics
physical aspects of interfaces
industrial interfaces

16. Ergonomics
• Study of the physical characteristics of
interaction
• Also known as human factors – but this can
also be used to mean much of HCI!
• Ergonomics good at defining standards and
guidelines for constraining the way we design
certain aspects of systems

17. Ergonomics - examples
• arrangement of controls and displays
e.g. controls grouped according to function or
frequency of use, or sequentially
• surrounding environment
e.g. seating arrangements adaptable to cope with all
sizes of user
• health issues
e.g. physical position, environmental conditions
(temperature, humidity), lighting, noise,
• use of colour
e.g. use of red for warning, green for okay,
awareness of colour-blindness etc.

18. Industrial interfaces
Office interface vs. industrial interface?
Context matters!
office industrial
type of data textual numeric
rate of change slow fast
environment clean dirty
… the oil soaked mouse!

19. Glass interfaces ?
• industrial interface:
– traditional … dials and knobs
– now … screens and keypads
• glass interface
+ cheaper, more flexible,
multiple representations,
precise values
– not physically located,
loss of context,
complex interfaces
• may need both
Vessel B Temp
0 100 200
113
multiple representations
of same information

20. Indirect manipulation
• office– direct manipulation
– user interacts
with artificial world
• industrial – indirect manipulation
– user interacts
with real world
through interface
• issues ..
– feedback
– delays
system
interface plant
immediate
feedback
instruments

21. interaction styles
dialogue … computer and user
distinct styles of interaction

22. Common interaction styles
• command line interface
• menus
• natural language
• question/answer and query dialogue
• form-fills and spreadsheets
• WIMP
• point and click
• three–dimensional interfaces

23. Command line interface
• Way of expressing instructions to the
computer directly
– function keys, single characters, short abbreviations,
whole words, or a combination
• suitable for repetitive tasks
• better for expert users than novices
• offers direct access to system functionality
• command names/abbreviations should be
meaningful!
Typical example: the Unix system

24. Menus
• Set of options displayed on the screen
• Options visible
– less recall - easier to use
– rely on recognition so names should be meaningful
• Selection by:
– numbers, letters, arrow keys, mouse
– combination (e.g. mouse plus accelerators)
• Often options hierarchically grouped
– sensible grouping is needed
• Restricted form of full WIMP system

25. Natural language
• Familiar to user
• speech recognition or typed natural language
• Problems
– vague
– ambiguous
– hard to do well!
• Solutions
– try to understand a subset
– pick on key words

26. Query interfaces
• Question/answer interfaces
– user led through interaction via series of questions
– suitable for novice users but restricted functionality
– often used in information systems
• Query languages (e.g. SQL)
– used to retrieve information from database
– requires understanding of database structure and
language syntax, hence requires some expertise

27. Form-fills
• Primarily for data entry or data retrieval
• Screen like paper form.
• Data put in relevant place
• Requires
– good design
– obvious correction
facilities

28. Spreadsheets
• first spreadsheet VISICALC, followed by
Lotus 1-2-3
MS Excel most common today
• sophisticated variation of form-filling.
– grid of cells contain a value or a formula
– formula can involve values of other cells
e.g. sum of all cells in this column
– user can enter and alter data spreadsheet
maintains consistency

29. WIMP Interface
Windows
Icons
Menus
Pointers
… or windows, icons, mice, and pull-down menus!
• default style for majority of interactive
computer systems, especially PCs and desktop
machines

30. Point and click interfaces
• used in ..
– multimedia
– web browsers
– hypertext
• just click something!
– icons, text links or location on map
• minimal typing

31. Three dimensional interfaces
• virtual reality
• ‘ordinary’ window systems
– highlighting
– visual affordance
– indiscriminate use
just confusing!
• 3D workspaces
– use for extra virtual space
– light and occlusion give depth
– distance effects
flat buttons …
… or sculptured
click me!

32. elements of the wimp interface
windows, icons, menus, pointers
+++
buttons, toolbars,
palettes, dialog boxes
also see supplementary material
on choosing wimp elements

33. Windows
• Areas of the screen that behave as if they
were independent
– can contain text or graphics
– can be moved or resized
– can overlap and obscure each other, or can be laid
out next to one another (tiled)
• scrollbars
– allow the user to move the contents of the window
up and down or from side to side
• title bars
– describe the name of the window

34. Icons
• small picture or image
• represents some object in the interface
– often a window or action
• windows can be closed down (iconised)
– small representation fi many accessible
windows
• icons can be many and various
– highly stylized
– realistic representations.

35. Pointers
• important component
– WIMP style relies on pointing and selecting things
• uses mouse, trackpad, joystick, trackball,
cursor keys or keyboard shortcuts
• wide variety of graphical images

36. Menus
• Choice of operations or services offered on the screen
• Required option selected with pointer
problem – take a lot of screen space
solution – pop-up: menu appears when needed
File Edit Options
Typewriter
Screen
Times
Font

37. Kinds of Menus
• Menu Bar at top of screen (normally), menu
drags down
– pull-down menu - mouse hold and drag down menu
– drop-down menu - mouse click reveals menu
– fall-down menus - mouse just moves over bar!
• Contextual menu appears where you are
– pop-up menus - actions for selected object
– pie menus - arranged in a circle
• easier to select item (larger target area)
• quicker (same distance to any option)
… but not widely used!

38. Menus extras
• Cascading menus
– hierarchical menu structure
– menu selection opens new menu
– and so in ad infinitum
• Keyboard accelerators
– key combinations - same effect as menu item
– two kinds
• active when menu open – usually first letter
• active when menu closed – usually Ctrl + letter
usually different !!!

39. Menus design issues
• which kind to use
• what to include in menus at all
• words to use (action or description)
• how to group items
• choice of keyboard accelerators

40. Buttons
• individual and isolated regions within a
display that can be selected to invoke
an action
• Special kinds
– radio buttons
– set of mutually exclusive choices
– check boxes
– set of non-exclusive choices

41. Toolbars
• long lines of icons …
… but what do they do?
• fast access to common actions
• often customizable:
– choose which toolbars to see
– choose what options are on it

42. Palettes and tear-off menus
• Problem
menu not there when you want it
• Solution
palettes – little windows of actions
– shown/hidden via menu option
e.g. available shapes in drawing package
tear-off and pin-up menus
– menu ‘tears off’ to become palette

43. Dialogue boxes
• information windows that pop up to
inform of an important event or request
information.
e.g: when saving a file, a dialogue box is
displayed to allow the user to specify the
filename and location. Once the file is
saved, the box disappears.

44. interactivity
easy to focus on look
what about feel?

45. Speech–driven interfaces
• rapidly improving …
… but still inaccurate
• how to have robust dialogue?
… interaction of course!
e.g. airline reservation:
reliable “yes” and “no”
+ system reflects back its understanding
“you want a ticket from New York to Boston?”

46. Look and … feel
• WIMP systems have the same elements:
windows, icons., menus, pointers, buttons, etc.
• but different window systems
… behave differently
e.g. MacOS vs Windows menus
appearance + behaviour = look and feel

47. Initiative
• who has the initiative?
old question–answer – computer
WIMP interface – user
• WIMP exceptions …
pre-emptive parts of the interface
• modal dialog boxes
– come and won’t go away!
– good for errors, essential steps
– but use with care

48. Error and repair
can’t always avoid errors …
… but we can put them right
make it easy to detect errors
… then the user can repair them
hello, this is the Go Faster booking system
what would you like?
(user) I want to fly from New York to London
you want a ticket from New York to Boston
(user) no
sorry, please confirm one at a time
do you want to fly from New York
(user) yes
… … …

49. Context
Interaction affected by social and organizational
context
• other people
– desire to impress, competition, fear of failure
• motivation
– fear, allegiance, ambition, self-satisfaction
• inadequate systems
– cause frustration and lack of motivation

50. Experience, engagement and fun
designing experience
physical engagement
managing value

51. Experience?
• home, entertainment, shopping
– not enough that people can use a system
– they must want to use it!
• psychology of experience
– flow (Csikszentimihalyi)
– balance between anxiety and boredom
• education
– zone of proximal development
– things you can just do with help
• wider ...
– literary analysis, film studies, drama

52. Designing experience
• real crackers
– cheap and cheerful!
– bad joke, plastic toy, paper hat
– pull and bang

53. Designing experience
• virtual crackers
– cheap and cheerful
– bad joke, web toy, cut-out mask
– click and bang

54. Designing experience
• virtual crackers
– cheap and cheerful
– bad joke, web toy, cut-out mask
– click and bang

55. how crackers work
sender
fill in web form
To: wxv
From: ..
receive email recipient
closed
cracker page
open
message
recipient clicks
cracker opens ...
very slowly
joke
links
open
cracker page
web toy
mask
sender
watches
progress

56. The crackers experience
real cracker virtual cracker
Surface elements
design cheap and cheerful simple page/graphics
play plastic toy and joke web toy and joke
dressing up paper hat mask to cut out
Experienced effects
shared offered to another sent by email message
co-experience pulled together sender can't see content
until opened by recipient
excitement cultural connotations recruited expectation
hiddenness contents inside first page - no contents
suspense pulling cracker slow ... page change
surprise bang (when it works) WAV file (when it works)

57. Physical design
• many constraints:
– ergonomic – minimum button size
– physical – high-voltage switches are big
– legal and safety – high cooker controls
– context and environment – easy to clean
– aesthetic – must look good
– economic – … and not cost too much!

58. Design trade-offs
constraints are contradictory … need trade-offs
within categories:
e.g. safety – cooker controls
front panel – safer for adult
rear panel – safer for child
between categories
e.g. ergonomics vs. physical – MiniDisc remote
ergonomics – controls need to be bigger
physical – no room!
solution – multifunction controls & reduced functionality

59. Fluidity
• do external physical aspects reflect
logical effect?
– related to affordance (chap 5)
logical state revealed in physical state?
e.g. on/off buttons
inverse actions inverse effects?
e.g. arrow buttons, twist controls

60. inverse actions
• yes/no buttons
– well sort of
• ‘joystick’
• also left side control

61. spring back controls
• one-shot buttons
• joystick
• some sliders
good – large selection sets
bad – hidden state

62. a minidisk controller
series of spring-back controls
each cycle through some options
–natural inverse back/forward
twist for track movement
pull and twist for volume
– spring back
– natural inverse for twist

63. physical layout
controls:
logical relationship
~ spatial grouping

64. compliant interaction
state evident in
mechanical buttons
rotary knobs reveal internal state
and can be controlled by both user
and machine

65. Managing value
people use something
ONLY IF
it has perceived value
AND
value exceeds cost
BUT NOTE
• exceptions (e.g. habit)
• value NOT necessarily personal gain or money

66. Weighing up value
value
• helps me get my work done
• fun
• good for others
cost
• download time
• money £, $, €
• learning effort

67. • in economics Net Present Value:
– discount by (1+rate)years to wait
• in life people heavily discount
– future value and future cost
– hence resistance to learning
– need low barriers
and high perceived present value
Discounted future

68. example – HCI book search
• value for people who have the book
helps you to look up things
– chapter and page number
• value for those who don’t …
sort of online mini-encyclopaedia
– full paragraph of context
… but also says “buy me”!!
… but also says “buy me”!!

69. Value and organisational design
• coercion
• tell people what to do!
• value = keep your job
• enculturation
• explain corporate values
• establish support (e.g share options)
• emergence
• design process so that
individuals value  organisational value

70. General lesson …
if you want someone to do something …
• make it easy for them!
• understand their values